516 



STRUCTURE AND CLASSIFICATION OF BIRDS 



Dromceus ; the other is smaller and further back in the 

 substance of the coracoid. 



The sternum (fig. 246) is an exaggeration of that of 

 Dromceus, being longer and more pointed posteriorly. Four 

 or five ribs articulate with it. 



The pelvis too, though very like that of the emu, is (fig. 

 247) an advance upon it in structure. There may be (C. 



CO, 



ca 



FIG. 246. STERNUM or CASSOWARY (AFTER MIVART). 

 c, coracoid groove ; mx, posterior eud. Other letters as in fig. 242. 



galeatus) or may not be an osseous union between pubis 

 and ischium and between ischium and ilium. 



The ostrich skull is rather unlike that of the other two. 



The vomer is very short ' and does extend back as far as 

 the articulation of the palatines and pterygoids. The latter 

 bones articulate not only with the basipterygoid processes 

 but with the basisphenoid ; they bear off the palatines, which 



1 ' W. GRUBER, ' Ueber das Thranenbein cler straussartigen Vogel,' &c., Bull. 

 Ac. Sci. St.-Pttersb. 1855, p. 161. It varies somewhat in length according to 

 FURBRINGER, and was found in one case to be not unlike the vomer of an 

 segithognathous bird. 



